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c#timeouthttpclientcircuit-breakerpolly
superninja
superninja

Reputation: 3411

Timeout and Retry Logic in Circuit Breaker pattern using Polly

I am implementing Circuit Breaker pattern with HttpClientFactory and Polly using this tutorial and here's the code below that i wrote based on my understanding of the tutorial. RetryHttpRequest class is the class where HttpClient is used. 

  services.AddHttpClient<IRetryHttpRequest, RetryHttpRequest>()
                    .SetHandlerLifetime(TimeSpan.FromSeconds(3))
                    .AddPolicyHandler(GetCircuitBreakerPolicy());

  static IAsyncPolicy<HttpResponseMessage> GetCircuitBreakerPolicy()
        {
            return HttpPolicyExtensions
                .HandleTransientHttpError()
                .CircuitBreakerAsync(5, TimeSpan.FromSeconds(30));
        }

  1. For SetHandlerLifetime, does the lifetime here mean per API request? So if I do retry for 3 times, each retry should take no more than 3 seconds. It is interesting that the default lifetime is 2 minutes which I think is too long.

  2. How does SetHandlerLifetime(TimeSpan.FromSeconds(3)) and CircuitBreakerAsync(5, TimeSpan.FromSeconds(30)) related to each other and work with each other?

Upvotes: 0

Views: 1767

Answers (1)

mountain traveller
mountain traveller

Reputation: 8156

SetHandlerLifetime(...) is not to do with the timeout of individual calls. It is about how long HttpClients provided by HttpClientFactory reuse the same HttpClientHandler, which provides a trade-off between optimising resources and reacting to external DNS changes.

For applying timeouts via HttpClientFactory, and combining that with retry policies, see Polly's documentation on applying timeout via HttpClientFactory.

Upvotes: 2

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